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Abstract <p>The article provides new materials on Fe–Ti mineralization in rocks of the Kusa-Kopan complex. It is shown that the change in the basicity of rocks in the process of differentiation is classical and consists of an increase in the amount of silica in late differentiates (from pyroxenites to leucocratic granites with intermediate varieties) with a tholeiitic (Fenner) trend. The normalized distribution of rare-earth elements and the degree of their fractionation indicate their coherent behavior in the process of magmatic differentiation. Features of noble-metal geochemical specialization lie in the complementarity of graphs of normalized contents of noble metals, which differ from each other only quantitatively. It has been established that the formation of rhythmic layering is due to the action of the mechanism of directional crystallization, through the movement from bottom to top of the solidification front (crystallization zone), consisting of crystalline liquidus phases when the residual melt is squeezed into the main volume with its enrichment in low-temperature components. When the composition of the melt is close to subeutectic, the process will acquire an “oscillating” character, in which the binding of melt components in the mineral phase (clinopyroxene) shifts the equilibrium and crystallization of another phase (plagioclase) becomes possible. At the stage of formation of the crystallization zone, (titanium)magnetite forms disseminated mineralization, but, as the solidification front moves from bottom to top, the mechanism of gravitational sedimentation begins to operate, which leads to its concentration in the form of veinlets among the crystalline liquidus phases. The peculiarities of the internal structure and chemical composition of ilmenite-titanium magnetite mineralization are explained by the existence of high-temperature (1300–1400°C) homogeneous phases of Fe–Ti minerals, in which, with slow cooling of the massif and autometamorphism, the system is re-equilibrated with the decomposition of solid solutions, crystallization of minerals of the spinel family, and the formation of magnetite veinlets in ilmenite.</p>

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Mineralogical and Geochemical Features of Fe–Ti Ore Occurrences of the Kopan and Matkal Massifs (Kusa-Kopan Complex, South Urals)

  • 期刊论文

  • 发表日期：

    2025年12月1日

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  • S. G. Kovalev,
  • S. S. Kovalev

摘要

Abstract

The article provides new materials on Fe–Ti mineralization in rocks of the Kusa-Kopan complex. It is shown that the change in the basicity of rocks in the process of differentiation is classical and consists of an increase in the amount of silica in late differentiates (from pyroxenites to leucocratic granites with intermediate varieties) with a tholeiitic (Fenner) trend. The normalized distribution of rare-earth elements and the degree of their fractionation indicate their coherent behavior in the process of magmatic differentiation. Features of noble-metal geochemical specialization lie in the complementarity of graphs of normalized contents of noble metals, which differ from each other only quantitatively. It has been established that the formation of rhythmic layering is due to the action of the mechanism of directional crystallization, through the movement from bottom to top of the solidification front (crystallization zone), consisting of crystalline liquidus phases when the residual melt is squeezed into the main volume with its enrichment in low-temperature components. When the composition of the melt is close to subeutectic, the process will acquire an “oscillating” character, in which the binding of melt components in the mineral phase (clinopyroxene) shifts the equilibrium and crystallization of another phase (plagioclase) becomes possible. At the stage of formation of the crystallization zone, (titanium)magnetite forms disseminated mineralization, but, as the solidification front moves from bottom to top, the mechanism of gravitational sedimentation begins to operate, which leads to its concentration in the form of veinlets among the crystalline liquidus phases. The peculiarities of the internal structure and chemical composition of ilmenite-titanium magnetite mineralization are explained by the existence of high-temperature (1300–1400°C) homogeneous phases of Fe–Ti minerals, in which, with slow cooling of the massif and autometamorphism, the system is re-equilibrated with the decomposition of solid solutions, crystallization of minerals of the spinel family, and the formation of magnetite veinlets in ilmenite.